Rubber tire



Patented Nov. 2, 1937 UNITED TATES PATENT OFFICE RUBBER TIRE I EardleyHazell, New York, and Stewart n.

l, Ogilby, West New Brighton, N. Y., assignors to United States RubberProducts, Inc., New

York, N. Y., a corporation of Delaware 19 Claims. (01. IEHG} Thisinvention relates to rubber tires and more particularly to pneumatictire casings having carcasses with cord comprising artificial silk.

In the manufacture of rubber-fibre material,

for use in cord tires and the like, a fabric, usually a cotton fabric,which may or may not be impregnated with rubber, as from a solventcement or aqueous dispersion of rubber or rubberlike material, is usedas a base material. This fabric which may be a square woven fabric orwhich may comprise cords, with or without filling threads, the latterfabric being merely a series of parallel cords, is usually first coatedwith a thin friction coating of rubber by passing the fabric through abath of aqueous dispersion of rubber, or a bath of rubber solvent cementor by frictioncalendering on to the fabric a rubber composition which ispreferably softened-with an organic solvent such as naphtha, gasoline orthe like. A "skim-coating" of rubber is then calendered on to the thustreated fabric either on one or both sides and the compositerubber-fabric material is bias cut for plying up in the preparation ofthe tire carcasses. In some cases, the skim coating of rubber iscalendered directly on to the bare cotton fabric. The patent toHopkinson No. 1,424,020 describes the preparation of a so-called i"weftless fabric or web fabric" by passing a fabric composed of a seriesof parallel cords 30 through a bath of an aqueousdispersion of rubberand joining the cords together by the dried M rubber deposit from thedispersion adhering to the cords after the same have been withdrawn fromthe bath. The parallel cords may be arranged so that each cord touchesthe cord on the other side of the same or they may be separatedany'desired distance as is well known in the art today. This rubbercoated material is then generally skim coated on one or both sides toform the 40 rubber-fabric material which is bias cut and used in themanufacturing of tire casings. The skim coating may be applied totherubber treated fabric by a calendering operation or if desired byfurther treatment with an aqueous dispersion 45 or a solvent solution ofrubber.

In these methods of producing the rubber-fabric material forplying upand vulcanizing together in the manufacture of the tire casings,adequate resistance to fatigue of the tire, and

50 sumcient adhesion between the fabric piles and the vulcanized rubberintermediate the fabric plies is obtained, it is believed, more byvirtue of the stray surface fibres of the cotton in the fabric beingimbedded in and tenaciously holding on to the rubber and teeth of rubberbeing em- 6 bedded between the twists of the cotton cords than by virtueof any strict adhesive bond be tween the rubber film and the cottoncords themselves. When the cotton of the usual tire cord fabrics isreplaced in whole or in part by arti- 10. ficial silk, the presentmethods of forming the rubber-fabric material are not satisfactory.Threads or cords made from artificial silk unlike those composed ofcotton, are substantially free from any stray surface fibres and when itis de- 15 sired to coat such artificial silk with rubber, the questionis not one of adequate adhesion by imbedding stray surface fibres intothe rubber layer but is believed one strictly of a direct adhesionbetween the rubber and the cellulosic composition 20 comprising theartificial silk filaments. In attempting to follow the teachings of theprior art in making tire casings with fabric comprising artificial silkcords, it was found that the resistance to flexing of the carcass wasinsuflicient to provide a tire casing that would stand up in servicewithout premature break-down and separation of the fabric plies.

The present invention relates to the manufacture of tire casingscomprising plies of fabric containing cords comprising artificial silkand vulcanized rubber intermediate the plies wherein there is anadequate adhesion between the vulcanized rubber and fabric piles and thefatigue resistance of the tire is of a sufficiently high value thatthere will be no premature failure of the tire in service because ofpoor flexing qualities of the tire carcass, or of poor adhesion betweenthe rubber and fabric plies.

According to the present invention, it has been found that adequatefatigue resistance and sufficient adhesion of fabric to rubber in thecarcass plies can be obtained by bonding the fabric containing cordscomprising artificial silk to the vulcanized rubber by a compositioncomprising new rubber and reclaim rubber and preferably containingproteinous material, for example, the solids deposit of a compositioncomprising rubber latex and an aqueous dispersion of whole tire recla mdispersed on casein.

In working out the present invention, fabric plies composed of parallelrayon cords made by theviscose process were used, but the invention isin no way limited to the specific type of artificial silk or the kind offabric used, nor is it limited to fabrics composed entirely ofartificial silk threads or cords, since the principles underlying theinvention are applicable to varying fabric constructions composed inwhole or in part or artificial silk made by any of the well-knownprocesses. The artificial silk used in obtaining the illustrating databelow was a viscose rayon of filaments of size 2'75 denier twisted '7turns per inch to the left. This yarn is equivalent in weight to about a21 cotton yarn. The cords used in making the weftless fabric werecomposed of 5 strands of this rayon yarn twisted 20 turns per inch tothe right and 3 of these plied yarns cable twisted 10 turns per inchleft hand twist.

As an indication of the relative fatigue resistance of tires made fromdifferent carcasses, adhesion and flexing tests were carried out on thevarious rubber-fabric constructions as follows:

Five of the cabled cords as above described are wound ofi spools anddrawn through the aqueous dispersion to be applied thereto under lowtension and are'wound spirally touching each other on to a duck linerwhich in turn is wrapped on to a steel drum 20 inches in diameterrevolving at a rate of 314 R. P. M. This means that the cord is movingthrough the solution at a rate of 2 inches per second about 8 inchesbeing immersed in the solution at one time. Between 10 and 50% of thesolution adhering to the cord is doctored off. In this way about 26 to28 cords per inch are laid down side by side. The operation describedabove takes about 15 minutes after which the solution and cords aredried on the same drum at a gradually rising temperature to preventblowing or blistering, reaching F. at the end. The drum is then cooledfor 10 minutes more and the fabric cut off together with the liner. Thisfabric is about 12" x 37" in size. In this way about 10 to 15 parts ofdispersion solids are put on to 100 parts of bare cord.

The following describes the preparation and curing of stripping pads forthe stripping test for comparing the adhesion of rubber to the rayonplies, with the adhesion of rubber to cotton plies.

The rubber composition used to form the rubber plies in all casescomprised:

Parts by weight Smoked sheet 100 Zinc oxide 40 Sulphur 3.5 Pine tar 1Stearic acid 2 Antioxidant 1.5 Accelerator .5

The above composition is merely illustrative of any of the variousrubber compositions used for skim coating between the fabric plies inbuilding up the carcass. In preparing and curing the stripping pads,.040 to .045" of the above stock is frictioned on to a heavy duckbacking and to this more of the same stock is plied as a skim coatingmaking the finished gauge of the material .075. Apiece 1%" by 10" ofthis material is taken and two solutioned cords stripped from the webfabric to be tested are laid side by side along its long direction aboutapart and about from each edge of the piece. These cords are pressedinto the stock a very little by hand. Besides these two cords fortesting, in

this case rayon cords stripped from the web fabric prepared as describedabove, two bare cotton Icords used as controls are laid and held inplace by a little cement at each end. This whole-piece is next put in aplaten press, the skim side covered with Cellophane, shimmed to .080"and 1200 lbs. of hydraulic pressure applied with 30 lbs. of steam for 60minutes. In this way, the cords are buried in the rubber stock until theupper surfaces are flush with the surface of the rubber stock.

The stripping test is made as follows: The ends of the two rayon cordsare clamped into one pair of jaws while the backing material of thepiece is clamped in another pair. The steady motion separating the jawsat the rate of 2" per minute is then produced, the pull on the cordsbeing recorded automatically on a graph. About 2 inches of cord arestripped out of the skim coat stock during the test. The two bare cottoncords are held in the same way. A hot stripping or adhesion test isconducted in the same way, the temperature of the whole being maintainedat 270 F. By an examination of the record, the average value of the pullin each case is found. Since the exact amount of the imbedding variesfrom piece to piece, the results of the cords under test are comparedwith the results of the bare cotton on the same piece, the final resultsbeing expressed as percent of pull of bare cotton.

The following describes the flexing test commonly used as a measure offatigue resistance as described in an article by Gibbons in Ind. Eng.Chemistry, Analytical Edition, volume 2, page 99, January 15, 1930. Inpreparing flexing pads for this test, the web fabric made as abovedescribed by passing the parallel cords through the aqueous rubberdispersion and drying on a liner, is

run through a calender and .014 of the skim coat rubber stock abovedescribed is put on the side away from the liner. The liner is thenstripped off the fabric and enough of the same skim coat stock put onthe other side (about .014") to make the total weight of the skim coatapplied equal to 20 ozs. per sq. yd. of material. Pads of G-plythicknesses are then made up from pieces cut from the skim coatedfabric, the cords of each ply running perpendicularly to the twoadjacent ones and the surfaces originally away from the liner keptuppermost or lowermost in all the plies. Each ply as added to the pileis rolled down by hand. The plied pad is next trimmed to fit' a mold 5"x 8" in size and is shimmed with tinfoil to a thickness of .490", thepressure developed during curing bringing the total thickness up to.500". The

pad is cured in a French press using low hydraulic pressure with steamat 30 lbs. for 60 minutes. After standing for at least 15 hours, twopieces 1" x 8" each are cut from the 6-ply pad and bent over a bicyclehub 5 in diameter carrying a load of 100 lbs. these pads are moved backand forth about the hub travelling about 2" away from the center of thepiece each time, so that a complete cycle means a travel of about 8" tothe piece. This flexing operation is continued from 9:00 in the morninguntil 12:00 at noon with a rest period of one hour without tension atnoon and the flexing continued from 1:00 to 5:00 and with a rest withouttension from 5:00 oclock at night to 9:00 oclock the next morning. Theend point of the By means of a motor,

flexing test is taken when a separation of one I The results of theflexing to cause this separation of plies. This flexing test is anindication of the fatigue resistance of the finished tire.

In attempting to use regular latex web fabric compounds with rayon cordsfor bonding the skim coat to the rayon fabric, the stripping tests withthe best compounds showed cold and hot adhesions 40% to 60% of that ofbare cotton. This adhesion while suflicient with a high flexing value,should preferably be considerably higher. The flexing tests, however,showed so low a flexing value that the fatigue resistance of tires madefrom such a carcass would not stand up at all in test.

According to the present invention, it has been found that a compositioncomprising rubber latex and an aqueous dispersion of reclaim rubber andcontaining proteinous material, when used to bond the skim coat to thecords, increases cold and hot adhesion and also increases the flexingresistance of the carcass, as determined by the flexing test. As shownin Table I, the solids deposit of a composition comprising rubber latexand casein dispersed whole tire reclaim in the proportion of 1 part oflatex solids to l to 4 parts of reclaim solids increases considerablyture of satisfactory tires.

-the cold and hot adhesion and the flexing value over straight latexcompositions, with or without added casein, and gives a suflicientlyhigh flexing test for the production of tires having adequate fatigueresistance.

The latex used in the various tests was of the following composition 7Parts by weight Rubber (as normal latex of about 36% solids) Sulphur n2.5 Zinc oxide 2.5 Sodium hydroxide .085 Accelerator .38 Antioxidant .63

The aqueous dispersion of reclaim rubber used in the tests was of thefollowing composition Whole tire reclaim (parts by weight)-.. 700

Casein do Borax clo 14.! Sodium fluoride", ..do 7.35. Water to per centtotal solids 50 The casein for dispersing the whole tire reclaim may besolubilized' by means of ammonia, lime or borax alone instead of withborax and sodium fluoride as in the above table as is well known in theart.

Table 1 Parts Casein Casein Cold Hot Flak Parts reclaim per 100 per 100adhesion adhesion mg latex disperparts parts percent percent knm solidssion total latex bare bare c ales solids solids solids cotton cotton y100- 0 0 0 44 60 22 100. 0 6 5 47 67 34 100- 0 l0 10 59 50 81 100. 0 202O 67 56 102 100. 0 40 40 9-5 88 61 100. Z5 2. 5 3. 2 100 82 38 100- 504. 2 6. 3 300 100 43 100 100 6. 3 12.7 167 122 100. 200 8. 5 25. 4 460300 252 100.- 400 10.0 50. 8 214 200 182 The casein may be present up to30% of the solids of the adhesive and still give a sufiiciently highflexing resistance to permit the manufac- As shownin Table I, thepreferred proportion of latex solids to reclaim solids is 1 to 2 and thecasein content.

about 10% (8.5%). In Table II the casein content of a composition havinga proportion of latex solids to reclaim solids of 1 to 2 was increasedby the addition of solubilized casein to the composition. As shown inTable II increasing the casein decreases the cold and hot adhesion butdoes not appreciably reduce the flexing resistance. The cold and hotadhesion, however, is not reduced sufficiently to deleteriously affect atire so long as the flexing resistance has been maintained at a highvalue.

While in the tests above, normal latex was used, it is obvious thatconcentrated or otherwise compounded latex may be used. Aqueousdispersions of other types of reclaim such as tube reclaim may be used,but it is preferred to use acarbon black-containing reclaim such aswhole tire reclaim. The reclaim may be dispersed on other proteinousmaterial, or if desired, the reclaim may be dismrsed on non-proteinousmaterials and proteinous material such as casein added to thecomposition containing the rubber latex and such aqueous dispersion ofreclaim. While the fabric in the above tables was composed of parallelcords made of viscose rayon, the principles underlying the presentinvention are applicable to fabrics made in part of such viscose rayonand in part of cotton or other fibres, and also of fabrics made in wholeor in part of cords composed in whole or in part of artificial silk madeby any of the other well known processes, such as the cuprammonium rayonprocess, which like the viscose process produces a regenerated cellulosenitro cellulose rayon process, cellulose acetate process and the like,and whether such artificial silk threads have been de-sulphurized ornot.

While the description in the present case is directed more particularlyto the manufacture of pneumatic tires, the fundamentals underlying thepresent invention are equally applicable to other products having pliesof fabric and vulcanized rubber intermediate the fabric plies, such ashose and the like, where the adhesion of fabric to rubber and theresistance to fatigue of the product are matters of importance. 4

As various other modifications will occur to those skilled in the art,it is not intended to limit the invention other than as set forth in theappended claims.

Having thus described our invention, what we claim and desire to protectby Letters Patent is:

1. A pneumatic tire casing having plies of fabric containing cordscomprising artificial silk and vulcanized rubber intermediatethe fabricplies, and the solids deposit of ,a composition comprising rubber latexand casein and aqueous disersed carbon black-containing reclaimed rubberparticles, bonding the said vulcanized rubber to the said fabric plies.

2. An article having plies of fabric containing cords comprisingartificial silk and-vulcanized rubber intermediate the fabric plies, andthe til and vulcanized rubber intermediate the fabric piles, and thesolids deposit of a composition comprising rubber latex and carbon blackand aqueous casein dispersed reclaimed rubber particles, bonding thesaid vulcanized rubber to the said fabric plies.

4. A pneumatic tire casing having plies of fabric containing cordscomprising regenerated cellulose and vulcanized rubber intermediate thefabric plies, and the solids deposit of a composition comprising rubberlatex and aqueous dispersed reclaimed rubber particles and containingcasein and carbon black, bonding the said vulcanized rubber to the saidfabric plies.

5. A pneumatic tire casing having plies of fabric containing cordscomprising regenerated cellulose and vulcanized rubber intermediate thefabric piles, and the solids deposit of a composition comprising rubberlatex and proteinous material and aqueous dispersed carbonblackcontaining reclaimed rubber particles, bonding the said vulcanizedrubber to the said fabric plies.

6. A pneumatic tire casing having piles of fabric containing cordscomprising artificial silk and vulcanized rubber intermediate the fabricplies, and the solids deposit of a composition comprising rubber latexand an aqueous dispersion of carbon black-containing rubber reclaimdispersed on a proteinous material, bonding the said vulcanized rubberto the said fabric plies.

'7. An article having plies of fabric containing cords comprisingartificial silk and vulcanized rubber intermediate the fabric plies, andthe solids deposit of a composition comprising rubber latex andproteinous material and aqueous dispersed carbon black-containingreclaimed rubber particles, bonding the said vulcanized rubber to thesaid fabric plies.

8. A pneumatic tire casing having plies of fabric containing cordscomprising regenerated cellulose and vulcanized rubber intermediate thefabric plies, and the solids deposit of a composition comprising rubberlatex and an aqueous dispersion of carbon black-containing rubberreclaim dispersed on casein, bonding the said vulcam'zed rubber to thesaid fabric plies.

9. An article having plies of fabric containing cords comprisingartificial silk and vulcanized rubber intermediate the fabric piles, andthe solids deposit of a composition comprising rubber latex .and aqueouscasein dispersed carbon blackcontaining reclaimed rubber particles,bonding the said vulcanized rubber to the said fabric plies.

10. A pneumatic tire casing having plies of fabric containing cordscomprising regenerated cellulose and vulcanized rubber intermediate thefabric plies, and the solids deposit of a composition comprising rubberlatex and aqueous casein dispersed carbon black-containing reclaimedrubber particles in the proportions of one part latex solids to one tofour parts reclaim solids and containing up to about 30% casein based onthe total solids, bonding the said vulcanized rubber to the said fabricplies.

11. An article having plies of fabric containing cords comprisingregenerated cellulose and vulcanized rubber intermediate the fabricplies,

and the solids deposit of a composition comprising rubber latex and anaqueous dispersion of carbon black-containing reclaim dispersed onproteinous material in the proportion of one part latex solids to one tofour parts reclaim solids, bonding the said vulcanized rubber to thesaid fabric plies.

12. A pneumatic tire casing having plies of fabric containing cordscomprising artificial silk and vulcanized rubber intermediate the fabricplies, and the solids deposit of a composition comprising rubber latexand aqueous casein dispersed whole tire carbon black-containingreclaimed rubber particles in the proportion of one part latex solids totwo parts reclaim solids and containing about 10% casein based on thetotal solids, bonding the said vulcanized rubber to the said fabricplies.

13. A process for bonding rubber to fabric containing cords comprisingregenerated cellulose, which comprises applying to the fabric a coatingcomposition comprising rubber latex and aqueous dispersed reclaimedrubber particles and containing proteinous material and carbon black,applying a vulcanizable rubber composition to the thus coated fabric,and vulcanizing the composite product.

14. A process for bonding rubber to fabric containing cords comprisingartificial silk, which comprises applying to the fabric a coatingcomposition comprislng rubber latex and proteinous material and aqueousdispersed carbon blackcontaining reclaimed rubber particles, applying avulcanizable rubber composition to the thus coated fabric, andvulcanizing the composite product.

15. A process for bonding rubber to fabric containing cords comprisingartificial silk, which comprises applying to the fabric a coatingcomposition comprising rubber latex and aqueous casein dispersed wholetire carbon black-containing reclaimed rubber particles in theproportion of one part latex solids to one to four parts reclaim solidsand containing up to about 30% casein, applying a vulcanizable rubbercomposition to the thus coated fabric, and vulcanizing the compositeproduct.

16. In the process of making a tire casing with cords comprisingartificial silk, the steps of applying to the cords a coatingcomposition comprising rubber latex and aqueous dispersed reclaimedrubber particles and casein and carbon black, drying, applying a layerof vulcanizable rubber over said first coating, and thereaftervulcanizing whereby the rubber layer will be securely bonded to thecords by the first coating.

17. In the process of making a tire casing with cords comprisingartificial silk, the steps of applying to the cords a coatingcomposition comprising rubber latex and aqueous casein dispersed carbonblack-containing reclaimed rubber particles in the proportions of onepart latex solids to one to four parts reclaim solids and containing upto about 30% casein based on the total solids, drying, applying a layerof vulcanizable rubber over said first coating and thereaftervulcanizing whereby the rubber layer will be securely bonded to thecords by the first coating.

18. In the process of making a tire casing with cords comprisingregenerated cellulose, the steps of applying to the cords a coatingcomposition comprising rubber latex and aqueous casein dispersed carbonblack-containing reclaimed rubber particles, drying, applying a layer ofvulcanizable rubber over said first coating, and thereafter vulpartlatex solids to one to four parts reclaim solids, drying, applying alayer of vulcanizable rubber over said first coating, and thereaftervulcanizing whereby the rubber layer will be securely bonded to thecords by the first coating.

EARDLEY HAZELL. STEWART B. OGI'L'BY.

